Engine starter



1945- J. w. FlTZ GERALD 2,366,502

ENGINE STARTER Filed Oct. 19, 1942 2 Sheets-Sheet 1 8mm i 31? M7. E72 gqrald 1945- J. w. FlTZ GERALD 2,365,502

ENGINE STARTER Filed Oct. 19, 1942 2 Sheets-Sheet 2 Patented Jan. 2, 1945 T or'ncs ENGINE STARTER John W. Fitz Gerald, Milwaukee, Wis., assignor to Briggs & Stratton CorporatiomMilwaukee', Wis., a corporation of Delaware Application October 19, 1942, Serial No. 462,544

4 Claims.

This invention relates to engine starters and refers particularly to starters for automobile engines of the type wherein the desired resiliency is provided by a resilient; coupling incorporating a collar of rubber or other similar material having cubical elasticity.

The rubber collar constitutes the sole torque transmitting connection between the driving and driven elements of the coupling, and to provide the desired resiliency and insure a secure grip between the collar and the driving and driven elements, the torque load must be applied in such a way that it places the collar under increasing endwise compression. This entails relative motion of the collar engaging flanges which consti tute the driving and driven elements toward each other during the operation of the starter.

Heretofore, this relative endwise motion was effected by arresting forward motion of the pinion and its part of the threaded connection which is used to advance and retract the pinion in such a way that the screw threaded part on the driven flange would be forced back 'by the screw action against the elasticity of the rubber collar until the engine load was overcome. This arrangement calls for a pinion stop fixed with relation to the motor shaft.

One mannerof providing this stop is to secure 'a collar to the motor shaft and against which the pinion abuts, but this expedient has objections, such as weakening the shaft and not having the entire starter structure self-contained.

Another manner of providing the stop and which obviates the latter of the previous objecgines.

It is, therefore, an object of this invention to provide a starter of. the-character described fwherein, thenecessary pinion stopcan bemounted on the hollowscrew shaft which is fixed to the driven flange-of the "resilient-coupling but inwhichother means are provided for placing the rubber collar of the coupling'under endwise .conrpression as the load of the engine ispicked .8 but'is free with respect thereto.

tion between the pinion and its actuating member, and wherein the required application of endwise compression on the rubber collar is'accomplished by camming the driving flange toward the driven flange as the load of the engine is picked up.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combinationand arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims. The accompanying drawings illustrate two complete examples of the physical embodiment of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a view inside elevation with parts broken away and in section of a starter embodying this invention and illustrating the same in its inoperative position;

Figure 2 is a view similar to Figure 1 but showing the starter in its operative engine cranking condition; and

Figures 3 and 4 are views similar to Figures 1 and 2 respectively but illustrating another embodiment of the invention.

Referring now particularly to the accompanying drawings, in which like numerals indicate like parts throughout theseveral views, the numeral 5 designatesthe pinion of an engine starter em- I bodying this invention and which during operation of the starter is propelled into mesh with the ring gear 6 of an engine to be'started.

The starter, indicated generally by the numeral 1, is mounted on the shaft 8 of a starting motor and comprises in addition to the pinion 5, an actuating member 9 drivingly connected with the motor shaft through a yieldable coupling II.

The actuating member 9-, which consists of a hollowscrew shaft H and 'a'fiange l2 integral therewith 'ismounted directly'on the motor shaft The pinion has a sleeve I3 projecting rearward- 1y therefrom and *telescoped over the screw mores ecincaily, it is an object of-this invention to provide *a'. starter so designedand constructed that thenecessary:pinion 'stop maybe conveniently embodied 'in the threaded "connec-' threaded actuating member with its rear end enlarged to receive a nut M." The nut I4 is threaded on the actuating member landis nonrotatably fixed to the pinion sleeve in any suitablefmanne'r as by interengagingflugsandf a: snap ring. --The pinion with its s eeye and nutlr'nay be regarded a a m? WWW Emma pinion member.

A stop collar I! fixed to the end of the screw threaded actuating member is engageable by the nut H to limit outward propulsion of the pinion and define its driving position shown in Figure 2.

In this position of the parts, the pinion member and the actuating member are in effect one unitary structure, adapted to be yieldingly driven from the motor shaft through the yieldable coupling H). The coupling It) consists of a collar I8 of rubber or other material having cubical elasticity and surrounding the motor shaft and confined between flange l2 of the actuating member and a driving flange IT.

The driving flange I! has a plurality of cams I8 thereon facing rearwardly and complementary to similar cams l9 carried by a collar 20 which is fixed to the motor shaft.

A sleeve or barrel 2| encloses the yieldable coupling and by inwardly directed edges 22 overlying the flange l2 and the collar 20, holds the coupling structure together under an initial degree of endwise compression. It is to be observed that the inwardly directed edges 22 form flanges having friction-clutch engagement with the driven flange l2 on the actuator and the flange of the driving collar 20, and that the expansive force of the elastic collar I8 holds these clutch surfaces in frictional engagement with the frictional grip increasing as the load of the engine is taken up.

When the pinion is meshed with the ring gear and the load of the engine is taken up, the driving torque applied to the collar 20 from the motor shaftwedges or cams the driving flange II forwardly toward the driven flange l2 to tighten the grip between these flanges and the elastic collar and to provide the desired resiliency through endwise compression of the elastic collar; and it is to be noted that this endwise compression of the collar is obtained without necessitating rearward displacement of the driven flange l2. When the pinion reaches the end of its stroke the friction clutch takes part of the torque, and the cam action by its increase of axial force as the torque increases transfers a large part of the torque to the friction clutch.

If during meshing of the pinion there is any interference with the advance of the pinion as by end-to-end abutment of its teeth with those of the ring gear the torque reaction upon the screw compresses the elastic collar sufliciently to disengage the friction-clutch, that is, flange l2 and its adjacent flange 22.

Consequently, meshing is effected more gently due to the elimination of the friction-clutch drive during this period.

The embodiment of the invention illustrated in Figures 3 and 4 is identical with that of Figures 1 and 2 except that instead of the complementary cams l8 and I9 through which the transmission of torque to the driving flange is accompanied by endwise displacement of the driving flange, a threaded connection 23 is provided for this purpose between the collar 20' fixed to the motor shaft and the driving flange IT. The operation and function of this form of the invention is identical with that described.

In both' constructions aconventional antireduction of the pinion diameter to the required minimum and at the same time provides the necessary action for establishing a power transmitting yieldable drive to the pinion.

What I claim as my invention is:

1. In an engine starter of the type having a pinion member and an actuating member threadedly connected so that relative rotation thereof effects endwise movement of the pinion member: cooperating means on said memebrs for limiting relative movement therebetween and defining the cranking position of the pinionmember; driving means for the actuating member including a yieldable coupling and a friction clutch, the resilient member of the yieldable coupling being arranged to exert pressure upon the friction clutch; cooperating inclined driving surfaces for augmenting the pressure upon the friction clutch as the load of the engine is picked up; and means to disconnect the clutch upon pinion tooth interference before contact of said cooperating limiting means on the pinion member and actuating member, said disconnecting means ineluding a plate adapted to press the resilient member of the yieldable coupling away from the clutch by the reaction of the threaded connection.

2. In a motor driven engine starter of the type having a pinion automatically propelled to and from an operative position: a yielding coupling and a friction clutch for transmitting torque tothe pinion, the resilient member of the yielding coupling being arranged to exert pressure upon the friction clutch; a screw and nut connection for shifting the pinion axially by relative rotation between the nut and screw;

cooperating stop means on the screw and nut engageable upon the pinion reaching its operative driving position and whereby said screw and ber and an actuating member: a screw fixedly connected to one of said members; a nut on the screw and fixedly connected to the other of said members; cooperating stops on the screw and nut engageable to define the operative projected position of the pinion and absorb the axial component of torque reaction upon the pinion within the screw and nut so that the pinion and actuating member are, in effect, one element when the pinion is in its operative projected position; a yieldable coupling and a friction clutch for connecting the actuating member with a .power source including a driven abutment on the acv tuating member between the yieldable coupling creep device 24 is provided which consists of a friction plug 25 spring urged'to ride on the threads of the actuating member.

and the friction clutch, whereby the axial reaction of the screw and nut upon pinion tooth interference moves the driven abutment away from the friction clutch and toward the yieldable coupling; a driving abutment; an elastic 2,866,502 driven collar and driving abutment for simultaneously transmitting torque to the driving abutment and for forcing the driving abutment contrary to the axial component of torque reaction upon the pinion toward the driven abutment against the resiliency of the elastic body; and a connection between said power driven collar and the actuating member for supporting the actuating member against endwise movement away from the power driven collar without interiering with relative rotation between said power driven collar and the actuating member, a portion of said connection being disposed as a. flange to form a friction surface of said friction clutch.

4. In an engine starter of the character described: a pinion; an actuator; means providing a threaded connection between the pinion and the actuator; stops on the pinion and actuator engageable to limit advance of the pinion by relative rotation between thepinion and actuator and thus cause said parts to move in unison; a yieldable coupling through which driving torque is transmitted to the actuator comprising driving and driven flanges disposed in planes normal to the axis of the starter; a power driven member adjacent to the driving flange; a resilient member in torque transmitting connection with the flanges and acting to thrust the flanges apart; means connected to the power drlven' member in friction clutch engagement with the driven flange and resisting the thrust of the resilient member; a torque transmitting connection between said power driven member and the driving flange having engaging helical surfaces, said torque transmitting connection constituting a lost motion driving connection whereby the transmission of torque to the driving flange results in forcing the driving flange toward the driven flange against the resiliency of the elastic collar in the presence of load on the driven flange; and. a connection from the actuator to the driven flange to move the driven flange out of engagement with the friction clutch and toward the yieldable coupling by reaction of the threaded connection upon interference with advance of the pinion during meshing.

JOHN W. F I'IZ GERALD. 

